This invention relates in general to sensing devices for measuring displacement of an object between first and second locations and, more particularly, to nonintensity-based sensing devices for measuring such displacement via optical techniques.
Many types of sensors rely on the ability of the sensor to measure linear displacement of an object in order to indirectly indicate changes in variables other than displacement itself. For example, pressure, temperature, torque and other types of sensors can function in this manner by using bi-metal strips, diaphragms and other structures to translate the sensed variable into a measurable displacement.
Modern electronic control systems for aircraft engines require that such sensors interface with electronic engine control circuitry. As the number of engine parameters which are monitored and controlled has significantly increased in advanced engine control systems, the demand for measurement accuracy from sensor devices has correspondingly grown dramatically. Unfortunately, to meet the demand for increased accuracy from such sensors, their complexity, cost, size and weight have undesirably tended to increase. Increasingly complex sensors are likely to be more susceptible to contamination than their earlier less complex counterparts.